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Author Topic:   The infinite space of the Universe
Straggler
Member
Posts: 10285
From: London England
Joined: 09-30-2006


Message 121 of 380 (468164)
05-27-2008 7:11 PM
Reply to: Message 116 by cavediver
05-27-2008 4:46 PM


Re: What is space?
Ok, for those with an actual interest in 'an' answer, the problem is what fields are we considering for this vacuum? If we're just talking about the 'basic' linear matter/force fields (quantum electrodynamics- i.e. photons & electrons) with a flat background metric (space-time), then we have the simple quantum vacuum state of the fields. There are no real particles in the vacuum state, but the fields are certainly not zero valued as is demonstrated by the Casimir Effect (by reducing the field vacumm fluctuations below that of the true vacuum).

This simple picture grows vastly more complicated when we hit the non-linear fields of Quantum ChromoDynamics and gravitation - their vacuum structures form global non-trivial backgrounds.


I am interested.
Where does the weak nuclear force fit into this? Does that have a field presence in the vacuum too? Do all 4 fundamental forces have an ever present field presence in every point of the vacuum?
How does the answer to this relate to a possible theory of everything?

This simple picture grows vastly more complicated when we hit the non-linear fields of Quantum ChromoDynamics and gravitation - their vacuum structures form global non-trivial backgrounds.

How does gravitataion have a field effect in the vacuum of curved spacetime when gravitation is curved spacetime? I am missing something fundamental here as this doesn't make sense to me?

This message is a reply to:
 Message 116 by cavediver, posted 05-27-2008 4:46 PM cavediver has responded

Replies to this message:
 Message 123 by cavediver, posted 05-28-2008 7:25 AM Straggler has responded

ICANT
Member
Posts: 6269
From: SSC
Joined: 03-12-2007
Member Rating: 1.4


Message 122 of 380 (468168)
05-27-2008 8:22 PM
Reply to: Message 118 by New Cat's Eye
05-27-2008 5:14 PM


Re: What is space?
Hi CS,

Catholic Scientist writes:

What's wrong with absolute nothingness being an impossibility? How is it a "paradox"?

What is wrong? We are Here.

If there was ever a time that there was absolute nothingness (an absence of anything) It would still be.

Energy can not be created therefore it had to always exist.

Or it can be created out of an absence of anything.

God Bless,


"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 118 by New Cat's Eye, posted 05-27-2008 5:14 PM New Cat's Eye has responded

Replies to this message:
 Message 126 by New Cat's Eye, posted 05-28-2008 10:17 AM ICANT has responded

cavediver
Member (Idle past 1981 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 123 of 380 (468177)
05-28-2008 7:25 AM
Reply to: Message 121 by Straggler
05-27-2008 7:11 PM


Re: What is space?
Where does the weak nuclear force fit into this? Does that have a field presence in the vacuum too?

Yes, it is another non-linear set of fields. This is where vacuum studies get very interesting as you're into the world of spontaneous symmetry breaking and the Higgs mechanism (and associated Higgs boson of course) In its most symmetrical state, what we think of as the electrodynamic fields (photons, electron, etc) are wrapped up into the eletcroweak fields. But this is not the lowest energy state. The true vacuum of the electroweak fields breaks the symmetry and we get the weak force and electrodynamics effectively splitting apart.

Do all 4 fundamental forces have an ever present field presence in every point of the vacuum?

Yes, though replace 'vacuum' with 'space-time' and you have the basic idea.

How does the answer to this relate to a possible theory of everything?

Well, a theory of everything at the very least has to unify the four 'force' fields and all the related matter fields into one master field.

How does gravitataion have a field effect in the vacuum of curved spacetime when gravitation is curved spacetime?

Ok, ready to go deep?

Reality as we see it is simply a multi-layer of fields. There is some pre-existing topology, so for example lets assume these fields are wrapped into a sphere (surface of a sphere), but its more like a stretchy empty bean-bag in that there is no concept of shape, geometry or distance - jut global topology. One field gives rise to a concept of 'distance'; at each point in the field, its values give the distance between neighbouring points at that location. Over the entire surface, this gives rise to the global shape, curvature and large scale distance. This is the gravitational or metric field. Its local values are given as a function of the values of the other fields at that point and the neighbouring values of its own field. Local fluctuations in this field give rise to gravitational waves, and at the qunatum scale, gravitons. The other fields are the ones we discussed above. This is the totality of reality. What we think of matter, space, vacuum, particles, people, stars, voids, curved space-time, etc, are all just aspects of this layer of fields.

Edited by cavediver, : No reason given.


This message is a reply to:
 Message 121 by Straggler, posted 05-27-2008 7:11 PM Straggler has responded

Replies to this message:
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 Message 127 by New Cat's Eye, posted 05-28-2008 10:25 AM cavediver has responded
 Message 136 by Straggler, posted 05-28-2008 4:42 PM cavediver has responded

Brad McFall
Member (Idle past 3370 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 124 of 380 (468178)
05-28-2008 7:29 AM
Reply to: Message 123 by cavediver
05-28-2008 7:25 AM


Re: What is space?
Thanks, I guess I am getting better with physics. That is pretty close to what I could have thought.

This message is a reply to:
 Message 123 by cavediver, posted 05-28-2008 7:25 AM cavediver has not yet responded

New Cat's Eye
Inactive Member


Message 125 of 380 (468193)
05-28-2008 10:04 AM
Reply to: Message 119 by Agobot
05-27-2008 5:50 PM


Re: What is space?
The fact that black holes do have mass does not rule out the possibility that they constitute true "nothingness".

:laugh:

It's a contradiction!

If the word nothingness does not signify anything meaningful, then there is no need for such a word. However, the word can be found in every dictionary and that is a paradox.

Its just a concept. Like absolute zero on the temperature scale. Nothing can ever really get to absolute zero but the concept exists as a benchmark.


This message is a reply to:
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New Cat's Eye
Inactive Member


Message 126 of 380 (468194)
05-28-2008 10:17 AM
Reply to: Message 122 by ICANT
05-27-2008 8:22 PM


Re: What is space?
Catholic Scientist writes:

What's wrong with absolute nothingness being an impossibility? How is it a "paradox"?

What is wrong? We are Here.

What's wrong with it being an impossiblity?

If there was ever a time that there was absolute nothingness (an absence of anything) It would still be.

Yupp. So nothingness is impossible.

Energy can not be created therefore it had to always exist.

Or it can be created out of an absence of anything.

Or two things that aren't energy themselves combine to become energy, like two branes colliding.

You're creating a flase dichotomy of either nothingness or eternal energy so that you can claim god. But lets ust leave god out of this thread, okay?


This message is a reply to:
 Message 122 by ICANT, posted 05-27-2008 8:22 PM ICANT has responded

Replies to this message:
 Message 131 by ICANT, posted 05-28-2008 2:58 PM New Cat's Eye has responded

New Cat's Eye
Inactive Member


Message 127 of 380 (468196)
05-28-2008 10:25 AM
Reply to: Message 123 by cavediver
05-28-2008 7:25 AM


Re: What is space?
Reality as we see it is simply a multi-layer of fields. There is some pre-existing topology, so for example lets assume these fields are wrapped into a sphere (surface of a sphere), but its more like a stretchy empty bean-bag in that there is no concept of shape, geometry or distance - jut global topology. One field gives rise to a concept of 'distance'; at each point in the field, its values give the distance between neighbouring points at that location. Over the entire surface, this gives rise to the global shape, curvature and large scale distance. This is the gravitational or metric field. Its local values are given as a function of the values of the other fields at that point and the neighbouring values of its own field. Local fluctuations in this field give rise to gravitational waves, and at the qunatum scale, gravitons. The other fields are the ones we discussed above. This is the totality of reality. What we think of matter, space, vacuum, particles, people, stars, voids, curved space-time, etc, are all just aspects of this layer of fields.

When they talk about the "bulk" in brane cosmology here:

quote:
In the brane picture, the other three forces (electromagnetism and the weak and strong nuclear forces) are localised on the brane, but gravity has no such constraint and so much of its attractive power "leaks" into the bulk.

Are they postulating that the multi-layer of fields exists within something else?


This message is a reply to:
 Message 123 by cavediver, posted 05-28-2008 7:25 AM cavediver has responded

Replies to this message:
 Message 128 by cavediver, posted 05-28-2008 10:49 AM New Cat's Eye has responded

cavediver
Member (Idle past 1981 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 128 of 380 (468200)
05-28-2008 10:49 AM
Reply to: Message 127 by New Cat's Eye
05-28-2008 10:25 AM


Re: What is space?
Are they postulating that the multi-layer of fields exists within something else?

I didn't actually specify a dimension of the reality before, but I guess we all assumed it was 4 dimensional (or 3 + time, depending on how you were picturing it.)

In a string/brane/M context, the dimension would be 10 + time, and our reality would exist as a 4d sub-slice of this higher-d space. So the effective fields that we see in 4d are only part of the real 11d fields. The bulk is the whole 11d space. Your quote is explaining that the effective 4d gravity is decomposed from the 11d in a slightly different way to the other effectuve 4d forces.


This message is a reply to:
 Message 127 by New Cat's Eye, posted 05-28-2008 10:25 AM New Cat's Eye has responded

Replies to this message:
 Message 129 by New Cat's Eye, posted 05-28-2008 2:14 PM cavediver has responded

New Cat's Eye
Inactive Member


Message 129 of 380 (468227)
05-28-2008 2:14 PM
Reply to: Message 128 by cavediver
05-28-2008 10:49 AM


Re: What is space?
Your quote is explaining that the effective 4d gravity is decomposed from the 11d in a slightly different way to the other effectuve 4d forces.

I got that part.

In a string/brane/M context, the dimension would be 10 + time, and our reality would exist as a 4d sub-slice of this higher-d space. So the effective fields that we see in 4d are only part of the real 11d fields. The bulk is the whole 11d space.

This answers my question. Thanks.

I wasn't sure if the 11d was the bulk or if the 11d was in the bulk, so to speak.

I didn't actually specify a dimension of the reality before, but I guess we all assumed it was 4 dimensional (or 3 + time, depending on how you were picturing it.)

Does the multi-layer of fields fall apart if you assume 11d instead of 4?


This message is a reply to:
 Message 128 by cavediver, posted 05-28-2008 10:49 AM cavediver has responded

Replies to this message:
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cavediver
Member (Idle past 1981 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 130 of 380 (468230)
05-28-2008 2:47 PM
Reply to: Message 129 by New Cat's Eye
05-28-2008 2:14 PM


Re: What is space?
Does the multi-layer of fields fall apart if you assume 11d instead of 4?

No, not at all. SuperGravity was our original attempt at an 11d theory of everything, which was essentially just a Grand Unification of all of the fields, including gravity. Now we suspect that there is something deeper than a 'simple' unification that gives rise to the picture of fields that I have described - string theory/M-theory being possibly behind this.


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 Message 129 by New Cat's Eye, posted 05-28-2008 2:14 PM New Cat's Eye has not yet responded

ICANT
Member
Posts: 6269
From: SSC
Joined: 03-12-2007
Member Rating: 1.4


Message 131 of 380 (468232)
05-28-2008 2:58 PM
Reply to: Message 126 by New Cat's Eye
05-28-2008 10:17 AM


Re: What is space?
Catholic Scientist writes:

Or two things that aren't energy themselves combine to become energy, like two branes colliding.

So are saying two branes are an absence of anything?

So how did they collide?

God Bless,


"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 126 by New Cat's Eye, posted 05-28-2008 10:17 AM New Cat's Eye has responded

Replies to this message:
 Message 132 by New Cat's Eye, posted 05-28-2008 3:02 PM ICANT has not yet responded
 Message 138 by onifre, posted 05-28-2008 6:13 PM ICANT has responded

New Cat's Eye
Inactive Member


Message 132 of 380 (468233)
05-28-2008 3:02 PM
Reply to: Message 131 by ICANT
05-28-2008 2:58 PM


Re: What is space?
So are saying two branes are an absence of anything?

:confused: What!? Are you joking? Of course they're not.

So how did they collide?

I dunno.

I was just pointing out that your two possibilities are not the only ones.


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 Message 131 by ICANT, posted 05-28-2008 2:58 PM ICANT has not yet responded

GDR
Member
Posts: 5043
From: Sidney, BC, Canada
Joined: 05-22-2005
Member Rating: 2.9


Message 133 of 380 (468249)
05-28-2008 4:30 PM


If they are able to find the Higg's bosun with the LHC will it move us very much closer to the TOE? Is it likely that they will find anything else that might help as well?

Replies to this message:
 Message 134 by cavediver, posted 05-28-2008 4:38 PM GDR has responded
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cavediver
Member (Idle past 1981 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 134 of 380 (468251)
05-28-2008 4:38 PM
Reply to: Message 133 by GDR
05-28-2008 4:30 PM


If they are able to find the Higg's bosun with the LHC will it move us very much closer to the TOE?

No, but not finding it might well do so :)

Is it likely that they will find anything else that might help as well?

Yes, there are many possibilities, from supersymmetric partners of the standard model particles (photinos, winos, zinos, selectrons, squarks, etc) to min black holes - lots of exciting stuff :)


This message is a reply to:
 Message 133 by GDR, posted 05-28-2008 4:30 PM GDR has responded

Replies to this message:
 Message 137 by GDR, posted 05-28-2008 4:44 PM cavediver has responded

onifre
Member (Idle past 1288 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 135 of 380 (468252)
05-28-2008 4:39 PM
Reply to: Message 133 by GDR
05-28-2008 4:30 PM


If they are able to find the Higg's bosun with the LHC will it move us very much closer to the TOE? Is it likely that they will find anything else that might help as well?

No, not in relation to the Theory of Everything. The Higgs, as I understand it, came after T=O. It will however, help us better understand the expantion.


All great truths begin as blasphemies

This message is a reply to:
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